You can’t lose 5,4 kgs of fat in a couple weeks without juice, so it’s a mix of fat, muscle, water.. you’re gonna be ok though. I’d probably soften this fat loss phase a little by adding a little more calories. That way you can keep more muscles e and not have much skin loose at the end.
Weight loss is often fast to start with and then slows down. Your body dumps lots of water weight first, and then your body settles down to burning fat, which is slower. So this is normal.
If you keep losing weight this fast for more than a month or two, then see a doctor. But it’s much more likely that this is just the normal fast initial drop of water weight, and things will slow down soon. (Don’t get discouraged when it does slow down!)